Light source



Jan. 12, 1943.

LIGHT SOURCE Filed July 16, 1940 rlllcoH/v :SWR/wrang. BY Maker-w A TTOR N EYS.

Patented `ian. l2, 1943 oFFicE ucm' somtcr-zl John R. Stirnkorb, Cincinnati, Ohio,

Science Laboratories, Inc., corporation of Ohio assigner to Norwood, Ohio. a

Application July 16, 1940, Serial No. 345,807

Claims.

Myinvention relates to types of light sources in which an arc is caused topass between suitable electrodes through an ionized gas in a sealed envelope. Such structures are used ior many purposes including, but without limitation, the production of ultra violet radiation for therapeutic, bacteriological, chemical and activation purposes, for the production of visible or invisible radiation for other uses, and for the production of visible radiations by the impingement of ultra violet radiation upon fluorescent substances. The envelope, depending upon the use oi' the light source, may be pervious or impervious to ultra violet radiation or may have a illtering effect. The nature of the ionized gas likewise does not constitute a limitation upon my invention. I shall describe my invention in connection with tube-like light sources in which an arc isproduced between electrodes in an ionized atmosphere containing mercury, so that the radiation immediately produced by the arc contains a large proportion of the ultra violet, and in which light source the interior of the envelope is coated with a fluorescent substance capable of changing the ultra violet radiation to visible radiation. In the light of the teachings herein contained the skilled worker in the art will understand how to apply my teaching to light sources for any of the uses mentioned above and to light sources of different shapes and arrangements of envelope and operating parts.

So-called fluorescent lights comprising an envelope inside of which is coated with uorescent substances and containing suitable electrodes between which an arc may be struck, together with means for producing initially an ionization of the gas in the tube, have hitherto been made and have been used in connection with so-called starting means, the eiiect of which is to apply power to the arc electrodes after the gas has become ionized, and to turn oil the initial ionizing means. While devices of a' number of diil'erent forms for the purpose have been proposed, their operation has not been entirely satisfactory. In some instances the power is applied prior to the production of a sufficiently ionized condition of the gas; and in general difficulty is had with tubes going out and failing to re-light.

It is a primary object of my invention to provide a new light source structure and a new combination of light source structure with external controlling means whereby all oi these diiiiculties are eliminated. It is a primary object oi my invention to provide starting means, the action of 'which is not dependent upon the time lag oi' some external and unrelated apparatus, but is directly dependent upon the state of ionization of the gas in the envelope. It is an object of'myinvention to produce an improved light source of simple,

inexpensive,but sturdy construction, of long life,

and positive in its action. It is my object to provide external controlling means of simpliiled and inexpensive character but positive and dependable in action. In particular, it is my object to provide a combination oi light source and controller which at all times is fully automatic in action and which serves not only to start the electrical activity in the envelope properly, but keeps the light source in continuous action so long as the power is applied.

These and other objects of my invention which will be set forth hereinafter or will be apparent to one skilled in the art uponreading these specifications, I accomplish by that certain structure and arrangement of parts of which Il shall now describe the aforesaid exemplary embodiment. Reference is made to the vdrawing wherein:

Figure l is a longitudinal section of my -xempiary light source.

Fig. 2 is a transverse section along the line 2-2 oi' Fig. 1.

Fig. 3 is a wiring diagram.`

Fig. 4 is a longitudinal section of one end a light source showing a modiiled structure.

Fig. 5 is a transverse secton thereof taken along the lines 5 5 of Fig. 4.

Briefly in the practicefof my invention, I provide initial ionization means and means closely adjacent the ionization means for the production of a preliminary and relatively short arc discharge, and I cause the occurrence of this discharge to operate external controlling means whereby the electrical power is made effective upon the main electrodes for the main arc discharge. 'Ihe .externalmeansA is also caused to de-energize the initial ionizing means, so that the life of the necessary operating parts of the light source is very greatly prolonged.

In Fig. l, I indicates an envelope, the interior of which is coated as at 3 with a fluorescent substance. At each end, the envelope is closed and is provided with a press 4, or 6. At each end of the tube also I have provided a socket means l and 8 iitted with prongs. 'I'he socket means 8 in the particular exemplary embodiment has contact prongs 9 and IU, while the socket 1 has contact prongs II, I2 and I3. I have shown a pair of terminal wires passing through each press. At one end of the tube, terminalwires I4 and I 5 extend into the tube and have theirv ends bent over and juxtaposed, as most clearly shown at I6 and I1 in Fig. 2. 'Ihe distance betweenA the bent-over portions IB and I1 is less than any :thereof taken distance between other portions of the wires if preferably the same. Wires I9 and 20 .pass through the press into the tube. Outside the tube they are connected respectively with contact prongs 9 and I0. The wire I9 has the turned-over portion' 2l', while the wire 20 has: a turned-over portion 22, not shown in Fig. l, but indicated in Fig. 3. An incandescent iilament 23 connects the wires I9 and 20.

A small glass tube 24 connected either into one of the presses or elsewhere into the base of the tube, as shown, serves as entrance means for a fifth electrode 25. The end of this electrode may be positioned within the tube or may be coterminous with it or may extend beyond it, depending upon the length of arc desired.

The operation of the device and one manner in which it may be connected up will'be clear from Fig. 3. Other circuits yto accomplish the same result will be clear to skilled workers in the art in the light of my teachings. One of the power terminals 26 is connected to the wire I5. The wire I4 is connected through a lead 21 to a relay switch RS, and through that switch to the wire I9 at the opposite end of the tube. The wire is connected through a choke 28 or other sulitable reactance to the other power lead 29. A spring 30 or its equivalent keeps the relay switch normally closed. It will now be clear that when the main switch MS is closed, a circuit is effected, which circuit includes thefilament I8, the connector 21 outside the tube, the filament 23 and the choke or other reactance 28. The filaments I8 and 23 are coated with refractory oxide or are otherwise associated with a substance on a suitable support which, when heated by the iilaments, will emit electrons to ionize adjacent gas within the envelope. Through the action of the ilament therefore, the gas in the envelope undlergoes a progressive and spreading ionization which takes an appreciable time to become eiective throughout the entire gaseous medium within the envelope. It is, however, very quickly effective adjacent the filament. Considering the bent ever portions I6 and I1`of the wires I4 and I5 (which portions are located closely adjacent each other), these portions are at diierent potentials due to the voltage drop across the iilament I8. Therefore, as soon as the ionization has progressed far enough, an initial arc-is struck between portions I6 and I1 still further intensifying, spreading and speeding up the action `of ionization. The fifth electrode 25 is connected by a lead 3| through the coil 32 on the magnet of the relay, to the power lead 29 as shown. Therefore, the fifth electrode 25 will be at opposite polarity from the wire portion I6 and will also be at'a different potential from the wire portion I1. When the ionization of the gas in the tube has progressed far enough, there will therefore be an arc discharge between I6 or I`1, or the filament i8, and the iifth electrode 25. v

In the meantime an action similar to that rst described has been going on at the opposite end of the tube where adjacent portions of the gas are being ionized by iilament 23. An initial arc may thus have been established between the wire portions 2| and 22 and/,or the filament 23. I prefer this structure because it speeds up complete ionization and makes for-a more positive action of the tube; -but my invention is ndt solimited. I may omit the filament 23 and connect together parts 2l and 22 so as to provide a single electrode at the opposite end of the tube.

When an arc discharge occurs between I6 and 25, suilicient current iiows through lead 3| to energize the relay switch RS.. When ,this happens the external connection between wires I4 -and I8 is broken by the switch. So long as the connection was eective, there was not suiilcient potential difference between I8 and I1 on the one hand and 2l, 22 on the other, to permitan arc to be struck the length of the tube. When the connection is broken, however, the arc flashes, primarily between electrodes I8 and 22. There will be little or no current now passing'through the filaments I8 and 23.

But it will be noted that the relay will not be energized until suilcient ionization has `taken place to permit the striking of the arc between members I5 and 25. With the proper placement of the electrode 25 with respect to electrodes I6 or I1, ionization sufficient to permit the striking of this arc, becomes the gauge of suiiicient ionization in the envelope to permit the striking of the main arc. 'I'he functioning of the starting means therefore is made dependent upon the actual ionization within the tube and not upon some unrelated external circumstance. The power is not applied to the main electrodes until ionization is complete enough to permit the tube to operate. Thus the striking of the arc or the starting of the tube is made much more positive and dependable. If at any time the ionization within the envelope should fail suificiently to permit the arc to be extinguished, the starting means which I have described immediately recommences the same series of operations to start the tube again. It is thus fully automatic in its action. In fact the application of the full power to the main electrodes is dependent upon a continuation of the arc between I1 and 25 for the actuation of the relay. The winding 32 of the relay may be so constructed as to furnish the necessary impedance for the control of the supplementary arc between the electrodes I1 and 25, or some other impedance may be included in the circuit of the electrode 25.

In a structure such as I have described, the starting time can be controlled by placing a resistance 43 across the filament I8, or between the base terminals I2 and I3. The resistance can be internal, i. e., within the envelope or base of the light source, or it can be external as part of the control circuits. It may be a xed resistance, or a variable resistance, and if the latter, it can be calibrated in terms of starting time.

In Figs. 4 and 5 I have illustrated a modied structure wherein wires 33 and 34 pass through the press 35. The ends of these wires are bent over in a U-shape within the tube. This leaves wire portions 36 and 31 juxtaposed to form electrodes. The downwardly bent ends 38, 39 of the wires may be connected by means of the filament 40, so that a larger space for a iilament is thus provided. A tube 4I corresponding to the tube 24, is shown in this instance as part of or welded to the press 35 and the supplementary electrode 42 is shown therein. The tube is bent over and the electrode terminates short of its end so as to give a long path for the supplementary arc. As already explained, however, the placement of the parts in the tube may be varied to gauge the degree of ionization which must be attained before the power is applied to the main arc electrodes.

Modifications may be made in. my structure without departing from the spirit of my invention. Having thus described my invention what I claim as new and desire to secureby Letters Patent, is:

1. In a light source, an envelope, arc electrodes, an atmosphere which may be ionized, and means for ionizing said atmosphere, and a supplementary electrode so positioned with respect to one of said first mentioned electrodes that when a potential difference exists therebetween an arc will be formed between said supplementary electrode and one of said main electrodes at a point of ionization of said gas suiiicient to permit the striking of an arc between said first mentioned electrodes, and means in connection with said light source whereby the formation of said a'rc between said supplementary electrode and a main electrode is rendered effective to apply to said main electrodes, a potential difference suflicient to cause the striking of said main arc.v

2. In a light source structure an envelope, an ioni'zable gas in said envelope, a pair of electrodes, means short-circuiting said electrodes so as to prevent the occurrence of substantial potential difference therebetween, means for ionizing said gas, a supplementary electrode, means for rendering effective between said supplementary electrode and a main electrode a potential difference sufficient to cause the striking of an arc when ionization of said gas has proceeded to a predetermined degree, and means in connection with said supplementary electrode for breaking the short-circuit between the main electrodes upon the occurrence of said arc.

3. In a light source, an envelope, a press, a pair of wires extending through said press and connected together inside said envelope by means of a filament, one of said Wires at least being in electrical connection with a part serving as a main arc electrode, a second main arc electrode filament, a supplementary electrode in said envelope located adjacent one of said structures,

means containing a switch for connecting said structures in series across power leads, circuit means for said supplementary electrode and means in said last mentioned circuit means for operating said switch responsive to ionization in said envelope, whereby upon the occurrence of an arc to said supplementary electrode the series connection between said structures is broken.

5. In a light structure an envelope containing ionizable gas, interspaced electrode means for a main arc, one at least of said means comprising interspaced portions connected by a filament whereby ionization may be started in said gas, said filament producing a voltage drop between said interspaced parts whereby upon initial ionization of said gas a short arc is struck between said lnterspaced parts whereby to increase the rate of ionization, a supplementary electrode in said envelope, means for applying potential to said supplementary electrode to produce an arc between it and one of said electrode structures,

6. In a light source combination an envelope, an ionizable gas in said envelope, main arc electrodes and a iilament for ionizing said gas, means for applying power to said lament, means directly responsive to the degree of ionization of said gas to apply a potential difference to said main electrodes for the striking of an arc, said means being also elective to interrupt the application of power to said filament, and a resistance shunting said filament to control starting time.

7. In a light source combination an envelope, an ionizable gas in said envelope, main arc electrodes and a lament for ionizing said gas, means for applying power to said lament, means directly responsive to the degree of ionization of said gas to apply a potential difference to said main electrodes for the striking of an arc, said means being also effective to interrupt the application of power to said filament, and a. resistance shunting said filament to control starting time, said resistance being variable and being calibrated in terms of starting timel 8. In a light source, an envelope, main arc electrodes, anv atmosphere which may be ionized, means for ionizing said atmosphere, and a supplementaryelectrode so positioned and having a separate power lead whereby it may be so energized with respect to one of said first mentioned electrodes, that a supplementary arc will not be struck between said supplementary electrode and said one of said main electrodes until a point of ionization of said atmosphere is reached sufficient to permit the striking of an arc between said main arc electrodes, so that the striking of said supplementary arc may, through a suitable circuit arrangement, be made to effect the energization of said main arc electrodes for starting a main arc discharge.

9. In a light source, an envelope, an ionizable gas in said envelope, electrodes for a main arc discharge therein, and for at least one supplementary arc to promote the ionization of said gas, filament means for initiating the ionization of said gas to permit the starting of said supplementary arc, and yet another electroderso related to one of said main arc electrodes, and having a separate power lead whereby it may be so energized with respect thereto, that an arc will not be struck therebetween until a point of ionization of said gas is reached sufiicient to permit the striking of an trodes.

10. In a light source, an envelope, a pair of terminal wires passing through said envelope, a

` main arc electrode in electrical contact with one of said wires, a filament in said envelope conand means in the circuit of said supplementary electrode for rendering effective upon said main electrodes a potential diierence suiilcient for the striking ofthe main arc therebetween.

nected between said wires, another main arc electrode at an interspaced point in said envelope and having a terminal wire passing through said envelope, and a fourth terminal wire passing through said envelope and bearing within it another electrode member, said last mentioned electrode member being so located and having a separate power lead whereby it may be so energized with respect to one of the remainder of said terminal wire and electrode elements, that an arc will not be struck between said supplementary electrode and any of said remaining elements until a point of ionization of said gas is reached sufiicient to permit the striking of an arc between said main arc electrodes.

JOHN a. s'rmnxoaa.

arc between said main arc elec- 

